Graphing a d.e. w/ a discountinous forcing function

hey all
i have the following d.e.
y''+y=f(t); y(0)=0, y'(0)=1;
f(t)={ 1 , 0<=t < pi/2
{ 0, pi/2 <=t < infinity
so i solved the d.e.
and i got
Y(t) = 1+sin-cost-U_pi/2[1-sint]
i did all the work, i just don't know how to go about graphing the funciton..
any help would be appreciated.